By Jim Geier, Wireless-Nets, Ltd.
I've been seeing a lot of companies with access point firmware that's not up-to-date. This means that these companies are not taking advantages of security and performance patches offered by the vendor. Take a look at your firmware and download updates as needed. Be certain to read over the vendor's notes, however, to ensure that installing the new firmware will not introduce any known issues that will adversely impact your network.
Tuesday, September 30, 2008
Thursday, September 25, 2008
Use WireShark instead of Ethereal
By Jim Geier, Wireless-Nets, Ltd.
Many of you may be still using Ethereal for obtaining packet traces of Wi-Fi networks. About a year or so ago, Gerald Combs, Ethereal's lead developer, left his company and couldn’t keep the name "Ethereal." As a result, Gerald renamed the software "WireShark" and has been supporting WireShark since then. Instead of using Ethereal, which I don't believe is being supported anymore, I recommend downloading the latest version of WireShark at www.wireshark.org. WireShark is still free and provides the same (and better) functionality as Ethereal.
Many of you may be still using Ethereal for obtaining packet traces of Wi-Fi networks. About a year or so ago, Gerald Combs, Ethereal's lead developer, left his company and couldn’t keep the name "Ethereal." As a result, Gerald renamed the software "WireShark" and has been supporting WireShark since then. Instead of using Ethereal, which I don't believe is being supported anymore, I recommend downloading the latest version of WireShark at www.wireshark.org. WireShark is still free and provides the same (and better) functionality as Ethereal.
Tuesday, September 23, 2008
Watch your back!
By Jim Geier, Wireless-Nets, Ltd.
You can implement the most effective encryption and authentication in the World, but someone can easily look over your shoulder and read your emails along with you. Airports are fairly open, making it easy for a hacker to also see your passwords as you type them in. So, keep this in mind as you utilize public Wi-Fi hotspots.
You can implement the most effective encryption and authentication in the World, but someone can easily look over your shoulder and read your emails along with you. Airports are fairly open, making it easy for a hacker to also see your passwords as you type them in. So, keep this in mind as you utilize public Wi-Fi hotspots.
Thursday, September 18, 2008
Wipe those mobile devices
By Jim Geier, Wireless-Nets, Ltd.
I've found that more and more companies are beginning to deploy device wipe functions to ensure that wireless hand held devices are secure in case they are lost or stolen. For example, an employee who's lost their device can inform a system administrator that the device is gone, and the administrator can issue a command to the device to wipe the memory and applications from the device. In case the device is out of range of the wireless network, functions on the device itself will automatically perform the wiping if someone mistakenly enters the wrong user name / password too many times. I don't believe that Windows natively supports the wiping functions, but I think that it's under development. Regardless, the device wiping seems to be a good security mechanism. Just be sure to do a good job of replicating data on a server!
I've found that more and more companies are beginning to deploy device wipe functions to ensure that wireless hand held devices are secure in case they are lost or stolen. For example, an employee who's lost their device can inform a system administrator that the device is gone, and the administrator can issue a command to the device to wipe the memory and applications from the device. In case the device is out of range of the wireless network, functions on the device itself will automatically perform the wiping if someone mistakenly enters the wrong user name / password too many times. I don't believe that Windows natively supports the wiping functions, but I think that it's under development. Regardless, the device wiping seems to be a good security mechanism. Just be sure to do a good job of replicating data on a server!
Tuesday, September 16, 2008
Elevation makes a difference
By Jim Geier, Wireless-Nets, Ltd.
I've found that many Wi-Fi hotspots in outdoor areas have very poor signal strength because the access point antennas are mounted relatively low to the ground, such as near the edge of roofs. The antennas propagate radio waves that must slice through people, buildings, and other obstacles to reach the users. Because of the resulting attenuation, it's generally better to install the access points (or just the antennas) higher up on light poles if they are available. The problem, however, is that it's difficult to run cabling to these higher mounting places. That’s when mesh network technology comes in handy.
I've found that many Wi-Fi hotspots in outdoor areas have very poor signal strength because the access point antennas are mounted relatively low to the ground, such as near the edge of roofs. The antennas propagate radio waves that must slice through people, buildings, and other obstacles to reach the users. Because of the resulting attenuation, it's generally better to install the access points (or just the antennas) higher up on light poles if they are available. The problem, however, is that it's difficult to run cabling to these higher mounting places. That’s when mesh network technology comes in handy.
Thursday, September 11, 2008
Inter-access point interference sometimes not a problem
By Jim Geier, Wireless-Nets, Ltd.
The common design rule for installing 802.11b/g access points is to set adjacent ones to non-overlapping channels (1, 6, and 11). This avoids the access points from competing for the same part of the spectrum, such as when transmitting beacons, data frames, and acknowledgements. When analyzing existing wireless LANs, however, I often find adjacent access points set to the same channel. In addition, it's common to have neighboring wireless LANs set to the same channels as yours. For example, a quick scan of my residential area shows several homes having access points all set to channel 6, the typical vendor default channel.
I've been analyzing various wireless LAN issues recently and ran some throughput tests between a wireless client and a particular access point - with and without the presence of another nearby ("interfering") access point set to the same channel. In fact, I measured degradation of a few percent in throughput when the interfering access point was active as compared to when it was not. This indicates that there's not much impact from the beacons of a neighboring access point set to the same channel. The problem, however, is when multiple clients are utilizing the interfering access point. That can take away a large portion of the bandwidth on your network.
The common design rule for installing 802.11b/g access points is to set adjacent ones to non-overlapping channels (1, 6, and 11). This avoids the access points from competing for the same part of the spectrum, such as when transmitting beacons, data frames, and acknowledgements. When analyzing existing wireless LANs, however, I often find adjacent access points set to the same channel. In addition, it's common to have neighboring wireless LANs set to the same channels as yours. For example, a quick scan of my residential area shows several homes having access points all set to channel 6, the typical vendor default channel.
I've been analyzing various wireless LAN issues recently and ran some throughput tests between a wireless client and a particular access point - with and without the presence of another nearby ("interfering") access point set to the same channel. In fact, I measured degradation of a few percent in throughput when the interfering access point was active as compared to when it was not. This indicates that there's not much impact from the beacons of a neighboring access point set to the same channel. The problem, however, is when multiple clients are utilizing the interfering access point. That can take away a large portion of the bandwidth on your network.
Tuesday, September 9, 2008
Wireless Network Implementation Guide
By Jim Geier, Wireless-Nets, Ltd.
I just started a newsletter titled the Wireless Network Implementation Guide. I focus each edition of the newsletter on a particular aspect of wireless networking. For example, the August edition of the newsletter discusses migration to 802.11n networks in enterprises. You can view past editions of the newsletter and subscribe to receive future editions at the following link: http://www.wireless-nets.com/resources/newsletter.html
I just started a newsletter titled the Wireless Network Implementation Guide. I focus each edition of the newsletter on a particular aspect of wireless networking. For example, the August edition of the newsletter discusses migration to 802.11n networks in enterprises. You can view past editions of the newsletter and subscribe to receive future editions at the following link: http://www.wireless-nets.com/resources/newsletter.html
Thursday, September 4, 2008
Wi-Fi robots on the run
By Jim Geier, Wireless-Nets, Ltd.
As part of some research I'm doing, I came across a website (Dr. Robot) advertising Wi-Fi robots. You can develop some pretty interesting systems with these devices. I've seen rather extensive use of Wi-Fi for robot communications in hospitals, but you have to ensure good coverage, or the robot gets lost!
As part of some research I'm doing, I came across a website (Dr. Robot) advertising Wi-Fi robots. You can develop some pretty interesting systems with these devices. I've seen rather extensive use of Wi-Fi for robot communications in hospitals, but you have to ensure good coverage, or the robot gets lost!
Tuesday, September 2, 2008
Defining requirements for wireless networking critical
By Jim Geier, Wireless-Nets, Ltd.
Before implementing a wireless network, you must define requirements to ensure what you’re deploying is based on the right things. Understand what constitutes valid requirements and learn about requirements that you might have overlooked by reading my latest tutorial.
Before implementing a wireless network, you must define requirements to ensure what you’re deploying is based on the right things. Understand what constitutes valid requirements and learn about requirements that you might have overlooked by reading my latest tutorial.
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